1. Field of the Invention
This invention relates generally to blow molding machines and more particularly to a method and apparatus for in-mold labeling of blow molded articles.
2. Description of the Prior Art
In-mold labeling is performed by inserting a label within the mold prior to the extrusion of the hot plastic tube and subsequent closing of sections of the mold in preparation for the blowing operation. The subsequent blowing operation forms the hot plastic tube around the label to the shape of the mold and activates a heat sensitive adhesive that provides a permanent bond which reduces the chances of being broken by moisture.
The prior art includes label carriers with vacuum cups that receive a label from a magazine and deposit the label within the mold cavity. Such vacuum carriers are sometimes mounted on levers or arms that move in an angular path with respect to the direction of opening and closing movement of corresponding mold sections in order to permit the deposit of the label.
Other prior art in-mold label dispensers include label carriers that move on an abruptly curved path and are actuated by complex linkage.
Still other prior art in-mold labelers include dispensing heads mounted for rectilinear movement along multiple axes. Somewhat complex coordination of mechanical systems is required to deliver labels to the open mold. Reference may conveniently be made to the U.S. Pat. Nos. 4,359,314, 4,397,625, 4,479,770 which are examples of the current state of the art.
In all of the prior art devices, the mechanisms employed have required arms or linkages which insert the label into the mold at a single point of intersection of the path of such mold with complex coordination mechanisms, thus requiring a slow operation with limited productivity.